As a repair method of existing conduits such as aging sewer pipes, a method to cover the entire inner surface of the conduit with inner face bars (lining materials) has been known (for example, refer to Patent Literatures 1 and 2).
As this kind of repair method, particularly with respect to repair of large-diameter conduits in which human workers can work inside the conduit, the present applicants have proposed a conduit repair method that can simplify repairing works and reduce repairing period without requiring a supporting during the repair (Patent Literature 3), and a repair method that can sufficiently reinforce conduits with severe degradation and deformed conduits wherein sufficient strength cannot be expected, and a conduit repair structure obtainable from such method (Patent Literature 4).
In the above-mentioned conduit repair methods, the inner face bars are made to be continuous in the conduit-longitudinal direction, so that they have an advantage that their flow capacity of the conduit can be increased because of seamless joint in the conduit-longitudinal direction; however, as the repaired length of the conduit increases, the total length of the inner face bars increases, resulting in difficulty in transportation or in manufacturing facility.
In addition, in a conduit repair structure in which a skeleton-like reinforcing body is used, during injection of a curable filling material, accumulated water and air in the conduit are mixed into the space between the inner face bar and the wall surface of the conduit near its bottom, which possibly leads to remaining of unfilled portions. In particular, in cases of conduits with a flat bottom such as horseshoe-shaped conduits and rectangular conduits (box culvert), the mixture of accumulated water and air tends to occur easily between the inner face bar and the wall surface of the conduit near its bottom, and unfilled portions are considered to be formed easily.
Under such circumstances, the applicants have proposed a conduit repair structure with easy handling and good workability at working site, which can solve problems related to transportation and manufacturing facility, by means of the following: inner face bars having a constant length in the conduit-longitudinal direction are installed in a conduit by being mutually contacted in their length and width directions, then they are integrated into a single object in the conduit (Patent Literature 5).
The applicants have also proposed a conduit repair structure wherein a notch is provided on an inner edge of a reinforcement body installed in the gap between the wall surface of the conduit and the inner face bar that covers said wall surface, and the notch serves to pass a curable filling material smoothly in the conduit-longitudinal direction, so that the flow of the curable filling material in the conduit-longitudinal direction is facilitated and development of unfilled portions of the curable filling material is prevented (Patent Literature 6).
FIGS. 11 to 14 show diagrams outlining conventional conduit repair structures related to the above proposed methods. In these conduit repair methods, a hollow frame reinforcement body consisting of a high-rigidity material (such as steel) is assembled inside a conduit, and an inner face bar (lining material) comprising resin or metal, etc. is attached inside this reinforcement body, then the space formed by this inner face bar and the wall surface of the conduit is filled with a curable filling material (grouting material).
For example, as shown in an example of FIG. 11, when the cross section of an existing conduit is circular, at first a reinforcing member 2 having a shape substantially along the inner wall of the conduit 1a is assembled inside the existing conduit 1. This reinforcing member 2 is assembled by mutually connecting a plurality of divided reinforcing members (in this case, three divided reinforcing members 2a, 2b and 2c) transported through a manhole, etc., to form a ring-like reinforcing member substantially along the inner wall of the conduit 1a as a whole. At the inside of this reinforcing member 2 in the conduit-diameter direction, a plurality of recessed parts for fitting (fitting section 2p) are formed at a predetermined pitch in the circumferential direction, the fitting section being used for fitting a fixing bar 11 with an inner face bar 30 as described later, and there are uniform concavities and convexities formed continuously at its outer edge in the circumferential direction.
In this ring-like reinforcing member 2, through holes 2q passing through in the conduit-longitudinal direction are formed at a constant interval in the circumferential direction; after installation of a plurality of the ring-like reinforcing members 2 inside the conduit at an interval, these ring-like reinforcing members 2 are connected and unified using connecting members consisting of pipe materials, bolts and nuts, etc. (figures not shown), with a certain interval in the conduit-longitudinal direction in the existing conduit, to form a hollow frame reinforcement body as a whole. In addition, at the inner edge of the reinforcing member 2, a notch 2r which is in communication with each of the through hole 2q is formed; therefore, even when the inner face bar 30 is attached, a gap that is in communication in the longitudinal direction of the existing conduit is formed near the inner edge of the reinforcement body 2 that is in contact with this inner face bar 30.
Next, as shown in FIG. 14, fixing bars 11 are attached to each of the fixing parts 2p of the reinforcing member 2 along the conduit-longitudinal direction of the existing conduit 1 in a mutually parallel manner, and inner face bars 30 are attached via these fixing bars 11. As shown in FIG. 12, this inner face bar 30 is a bilaterally symmetric strip-like body with a uniform cross section having a constant length of, for example, approximately 5 cm, which is integrally molded with a strip-like main body 30c and protruding sections for fitting 30a and 30b that are protruding to one side at the both edges of the body section 30c. A distance between the protruding sections for fitting 30a and 30c is identical to the distance (pitch) between the fixing parts 2p formed at inside of the reinforcement body 2; these inner face bars are inserted into the opening of the fixing bar 11 under the condition that the protruding section 30a of one of the mutually adjacent inner face bars 30 is in alignment with the protruding section 30b of the other of the mutually adjacent inner face bars 30. The inner surface formed by these multiple inner face bars 30 in the conduit-diameter direction forms the inner surface of the conduit after repair, as a repaired surface. Meanwhile, in some cases a sealing member 12 for the purpose of waterproof may be installed between the protruding sections for fitting 30a, 30b and the fixing bar 11.
Thereafter, as shown in FIGS. 13 and 14, a curable filling material is injected into the gap between this inner face bar 30 and the inner wall of the conduit 1a, to form a filling-material layer 3. Thus-injected curable filling material fills a compartment of the gap divided by each of the ring-like reinforcing member 2 in the conduit-longitudinal direction, from the bottom side of the already-existing conduit, while flowing through the gap formed by convex-concave of the outer edge of the reinforcing member 2, or the gap formed near the inner edge of the reinforcing member 2 due to the above-mentioned notches 2r, sequentially from one gap compartment to the next gap compartment.